Thermal Tolerance of Avian Embryos: A Review

摘要: Avian eggs usually experience temperatures of 30 to 400C during the incubation period, but often cool much lower temperatures. Hyperthermia is less common. Passerines do not show higher than other orders that have been studied extensively. Field measurements are optimal for development found in laboratory studies. Some species regulate egg closely throughout incubation; at least one penguin species, mean temperature increases and ranges decrease through period. Both continuous exposure range producing high survivorship differ among species. Species also their responses exposures limited duration. Thus, use a "physiological zero" applicable all warranted. Penguins both optimum broader acceptable studied. Age, duration, significantly affect survivorship. evidently more injurious developing embryo hypothermia. Resistance cold heritable trait, genetics physiology response(s) known. For older embryos, physiological effects hyperthermia similar those adult birds terms organ systems first fail. An estimate thermal tolerance short most 16 41 C and, lasting several hours, 36 390C.